feat: Introduce claude code and setting files (#3143)

[KATO-Hiro]

#3143

Summary by CodeRabbit

• Documentation

  • Added comprehensive guidelines covering authentication, database/migration practices, Svelte component conventions, testing patterns, project overview/tech stack, and on-demand agent rules; introduced a central AGENTS reference and Claude-specific guidance.

• Chores

  • Updated development container and environment to enable Claude tooling with persistent auth and adjusted install/startup commands.
  • Tweaked Docker build dependency install step to relax lockfile enforcement.

[coderabbitai]

Walkthrough

Adds Claude Code integration and developer guidance: new centralized docs (AGENTS.md, CLAUDE.md), four path-specific rule files under .claude/rules/, dev-notes/plans, devcontainer updates to persist Claude credentials and install the Claude CLI, and a Dockerfile change removing pnpm's frozen lockfile flag.

Changes

Cohort / File(s)	Summary
Claude rules .claude/rules/auth.md, .claude/rules/prisma-db.md, .claude/rules/svelte-components.md, .claude/rules/testing.md	Adds four new rule documents covering authentication (Lucia v2 patterns), Prisma/database conventions and migrations, Svelte component and store conventions, and testing guidelines (unit/integration/E2E patterns).
Project documentation AGENTS.md, CLAUDE.md	Introduces AGENTS.md as centralized project guidance and a concise CLAUDE.md that references rule files and formatting recommendations.
Devcontainer configuration .devcontainer/devcontainer.json, docs/dev-notes/2026-02-08/introduce-claude-code/plan.md, docs/dev-notes/2026-02-08/simplify-claude-md/plan.md	Devcontainer now mounts host ~/.claude, creates the directory on init, installs the Claude Code CLI, adds the anthropic.claude-code VSCode extension, and sets container env vars; includes plans/notes documenting the approach and rationale.
Build config Dockerfile	Modifies dependency install step to run pnpm install without the --frozen-lockfile flag (removes strict lockfile immutability).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I hopped into files at the break of day,
Rules and docs in tidy array,
Containers humming, CLI in tow,
Prisma, Svelte, tests all grow,
A tiny patch, a forward-play — hooray!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main changes: introduction of Claude Code support and configuration files across documentation, dev container, and rules.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch #3143

---

No actionable comments were generated in the recent review. 🎉

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[coderabbitai]

Actionable comments posted: 8

🤖 Fix all issues with AI agents

In @.claude/rules/auth.md:
- Around line 3-6: Update the glob that currently reads "src/lib/server/auth/**"
to the specific file path "src/lib/server/auth.ts" so it matches the actual file
(replace the glob string in the rules block where "globs:" contains
"src/lib/server/auth/**"); ensure the updated entry exactly reads
"src/lib/server/auth.ts" and remove or replace the erroneous directory-style
glob.

In @.claude/rules/testing.md:
- Around line 14-18: Update the Unit test "Location" entry in the test table:
change the pattern shown for Unit tests from `src/**/*.test.ts` to
`src/test/**/*.test.ts` so it matches the layout described on Line 22 and
AGENTS.md and consistently reflects that unit tests live under the `src/test/`
directory.
- Around line 46-49: AGENTS.md is missing the documented "pnpm coverage" command
referenced in .claude/rules/testing.md; add an entry for "pnpm coverage" to the
Commands section of AGENTS.md that explains it runs the test coverage reporter
(and mention the project targets: 80% lines, 70% branches as specified in
.claude/rules/testing.md) so users can discover and run the command; include the
exact command string "pnpm coverage" and a brief one-line description in the
Commands list to match the testing rules.

In @.devcontainer/devcontainer.json:
- Around line 9-12: The devcontainer mounts assume host ~/.claude exists which
can lead Docker to auto-create a root-owned directory; update
.devcontainer/devcontainer.json to either add a postCreateCommand that checks
for and creates ~/.claude on the host with correct ownership or add
documentation/instructions to run `claude login` on the host before opening the
container; reference the "mounts" array and add a "postCreateCommand" entry (or
README note) that creates the host ~/.claude (or instructs the user to run
claude login) to prevent root-owned auto-created directories and permission
issues inside the container.
- Line 25: The devcontainer's postCreateCommand currently only installs the
global Claude Code CLI (the "postCreateCommand" entry with "npm install -g
`@anthropic-ai/claude-code`") but does not install project dependencies tracked by
pnpm (pnpm-lock.yaml); update the postCreateCommand to run pnpm install as part
of the command chain (e.g., run pnpm install then the npm global install, or run
them joined with &&) so the container automatically installs project
dependencies and the global CLI on creation.

In `@AGENTS.md`:
- Line 12: Update the devcontainer port forwarding so the development server
port matches the README: open .devcontainer/devcontainer.json and modify the
forwardPorts array (the forwardPorts setting) to include port 5174 instead of
(or in addition to) 5173 so the container forwards localhost:5174 used by the
dev server described in AGENTS.md.

In `@docs/dev-notes/2026-02-08/simplify-claude-md/plan.md`:
- Around line 101-104: The fenced code block containing the authentication flow
diagram in plan.md lacks a language identifier; update the block that starts
with ``` and includes the flow "A[ユーザー登録] → B[AtCoder認証コード生成] →
C[AtCoder側でコード確認] → D[認証ステータス更新] → E[セッション作成] → F[ログイン完了]" to use a language
identifier (e.g., change ``` to ```text) so the fenced block is properly marked
and remains closed with a matching ``` fence.
- Around line 21-31: Update the fenced code block in plan.md that lists the
repository layout (the block starting with "AGENTS.md                    #
メイン（約50行）- Codex/Claude 共通" and ending with ".github/instructions/        #
削除（Copilot専用、情報が古い）") to include a language identifier (e.g., change ``` to
```text) so the diagram is rendered correctly and tooling/static analysis no
longer flags the block.

🧹 Nitpick comments (2)

.devcontainer/devcontainer.json (1)

93-95: NODE_OPTIONS applies globally to all Node.js processes.

--max-old-space-size=4096 and --dns-result-order=ipv4first will affect every Node process in the container (dev server, build, tests, Prisma CLI, etc.), not just Claude Code. The plan document acknowledges this trade-off. Just flagging for awareness — if any Node tooling misbehaves, this is a likely culprit.

CLAUDE.md (1)

1-1: Nit: heading repeats the filename.

Consider a more descriptive heading like # Claude Code Guidelines instead of # CLAUDE.md.

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@docs/dev-notes/2026-02-08/simplify-claude-md/plan.md`:
- Line 175: The line containing the truncated fragment "コードが正" in the document
(the sentence that begins "4. **認証フロー図は実態と異なっていた**:
ドキュメントの図と実装が乖離していたため、移管せず削除。コードが正") should be completed to a full sentence—e.g.,
"コードが正しいため移管の必要がなかった" or another intended ending—so update that sentence in
plan.md to a grammatically complete statement, preserve the Japanese
wording/context, and run a quick spell/encoding check to ensure no other
truncation remains.

[KATO-Hiro]

LGTM